The NV 242 Selectrac is a great transfer case but has some quirks you have to be aware of. For one, the tires should be the same size, brand and inflation pressure. Next, they shift best when you are driving over 20 mph, in a straight line. If you are going too slow or turning when you shift it will hang up in part time. Last it helps to lube all the the pivots for the shift linkage with motor oil.
Shifting into 4x4, hold it against the stop in the linkage and let off the gas. You can feel it pop in. Shifting back to 2wd, let off the gas.
2007 WK Limited Hemi QDII
1998 ZJ Laredo 4.0 Selectrac